Bridge Topology

NOTE: This feature is not available in NCache Express and Professional edition.

Remote data replication is a critical component for any plan to ensure effective and efficient protection and rapid recovery from a major interruption. Synchronous replication of data is good internally for the cluster but its impact on performance becomes a significant consideration when two clusters of cache are geographically separated. Bridge topology is designed for the scenarios which involve replication of data from one on-site cache to one/multiple and on-site/off-site disaster recovery cache(s) across the WAN. Due to asynchronous replication, all clients connected to the active cache(s) get an impression that the operations are being performed on the active cache while a complete backup is taken to the other cache(s) seamlessly.

When an operation is performed on source cache, it is asynchronously handed over to the bridge cache. This operation is then enqueued to a queue maintained by the bridge cache. Operations from the queue are transferred to the other cache(s) when bridge finds the cache(s) available and ready to accept operations. With the bridge topology, it is ensured that:

There is no performance degradation.

Operations are performed in same sequence as they were on original cache.

Operations are not lost in case of connection failure.

Below are the main bridge topologies provided by NCache:

Active Passive (One active and one passive cache)

Hub and Spoke (One active and multiple passive caches)

Active-Active (Only two active sites and no passive cache)

Star (All caches are active)

Active Passive (One active and one passive cache):

Three NCache Clusters participate in Active Passive topology:

An active cache (replicated, partitioned, mirror or partitioned replica), where all clients are connected and perform read and write operations.

A passive cache (replicated, partitioned, mirror or partitioned replica), where all operations performed on an active cache are replicated. Clients can connect to passive cache and perform both read and write operations but those operations are not replicated to the other caches. Modification can be done at passive cache if required.

A Bridge Cache between the active cache and the passive cache.

Hub and Spoke (One active and multiple passive caches):

Here at least three NCache Clusters participate in this topology:

An active cache (replicated, partitioned, mirror or partitioned replica), where all clients are connected and perform read and write operations.

Multiple passive caches (replicated, partitioned, mirror or partitioned replica), where all operations performed on an active cache are replicated. Clients can connect to passive caches and perform both read and write operations but those operations are not replicated to the other caches. Modification can be done at passive caches if required.

A Bridge Cache between the active cache and multiple passive caches.

Active-Active (Only two active sites no passive cache):

Three NCache Clusters participate in Active-Active topology:

Two active caches (replicated, partitioned, mirror or partitioned replica), where all clients are connected and perform read and write operations. Here any updates to the cache are applied asynchronously to the other cache.

A Bridge Cache between both the active caches.

Star (All caches are active):

Here at least three NCache Clusters participate in this topology:

Multiple active caches (replicated, partitioned, mirror or partitioned replica), where all clients are connected and perform read and write operations. Here any updates to the cache are applied asynchronously to all other caches.

A Bridge Cache between all the active caches.

Note:

Passive Caches when get connected to the bridge will be first cleared before connection establishment.